Steam generator



June 26, 1945. M H KUHNER 27,379,009

STEAM GENERATOR Les I|I|||||||t v l i MAX H. KUHNER I @a Q6@ gw@ L \\\w a l June 26, 1945. M KUHNER 2,379,009

STEAM GENERATOR l Filed Feb. e, 1945 l 2 Sheets-sheet 2 Fig-.4

. j A MAX H. KUHNER E www,

Patented June 26, 1945 UNITED STATES PATENT OFFICE f l.2,3'1'94109 STEAM GENERATOR Max H. Kuhner, Worcester, Mass., assgnor to `Riley Stokerl Corporation, Worcester, Mass., aV corporation of Massachusetts l Application February 6, 1943, Serial No. 474,913

8 Claims;

This invention relates to steam generators and more particularly to apparatus capable of utilizing the heat from the combustion of fuel .to -produce steam and to superheat the steam -t o ahigh temperature.

It is one object of the invention to provide a steam generator which will have a large capaci-ty in relation to the lloor space occupied.

It is a further yobject of the invention -to' provide a steam generator which will be thoroughly dependable in service and Capable of superheating steam to unusually high temperatures.

It is a further object of the invention to provide a steam generator having a new and highly efficient arrangement of Itubular superheater elements through which the steam'will travel in counterow relation to vhot gases of combustion.

It is a further object of the invention to provide a steam generator having a high temperature superheater so arranged and supported as to facilitate installation of the various elements.

It is a further object of the invention to provide a steam generator having a superheater, with a new and advantageous arrangement of -water cooled baiiles to direct hot gases Vinto counter-flow heat-transfer relation with the superheater.

It is a further object of the invention to provide a steam generator having a superheater, with a new and advantageous arrangement for allowing a controlled portion of the hot gases tov by--pass the superheater, so that the steam temperature can be controlled.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set wall I4, a rear wall l5, a roof IS, and tWo side walls I'I (one only being shown). The feront wall I4 is spaced a considerable distance forwardly frornthe tujbe bank. The lower front portion of the setting.

is utilized as a combustion chamber i9 .provided with a rear wall '2 0 having a burner opening 2i therein for the introduction-of a vsui-tableffuel, such as gas or oil. This wall 2B is located forwardly with respect to the lower drum I I, and this drum is elevated suiciently 'to allow ready access to the burner opening 2 I The combustion chamber I 9 is preferably cooledl by suitable water walltubes adjacent some lor all of its walls. For this purpose a header 23 is provided at the bottom of the rear wall 20, and a header l24 is provided at the bottom of each side wall Il, these headers VJ 2li being connected to the adiacent ends ofthe header 23, Water -issuppliecl to the Iheader `23 -fromlthe `lower drum I I Aby a, row of downcomer tubes 25 located behind the wall 20 and offset laterally from the burner opening 2l. From each of the headers-'24 a row of water wall f tubes 2l extends upwardly along the correspondonly the lower portions of the side water lWall superheater, certain refractory material being retubes 2-'I are shown in Fig. l. A header 3| is mounted adjacent the front wall yHI and intermediate the height of this wall. A row of water tubes 32 extends forwardly from the rear header 23 to the front wall I 4 and `thence upwardly along this -wall tothe header 3| the lower portions of these tubes supporting refractory material 33 -to provide a oor for the combustion chamber. From the header 3lI two rows of water tubes 36 extend upwardly and rearwardly to connect with the front portion of the upper drum I0, the tubes in each of these rows-being spaced apart rather widely. A. row of water tubes 36 extends Vupwardly from the rear Vheader 23"along the rear wall 2G and thence upwardly and forwardly to a vtransverse header 31 which is spaced rearwardly from the front wall I4. These Itubes 36 support refractory material 38 to .provilea roof for the `combustion chamber. VFrom the header 3l a row of water tubes Ml extends upwardly and rearwardly -to connect with the front portion of the upper drum Il), these -tubes 40 being positioned between the tubes 34 in the lower row. From the lower drum I I a row of water tubes 4I extends forwardly between the 'tubes 3.6 beneath the `combustion chamber roof 38 and then Vloops upwardly and rearwardly to a position slightly in front of the tube bank I2, whence it extends upwardly and connects with the front portion of the upper drum I in the same line as the upper row of tubes 34.

The hot gases leaving the combustion chamber I9 are directed into contact with steam superheating surfaces and then into the lower portion of the water tube bank I2. For this purpose the refractory 3 8 is extended forwardly and upwardly along the tubes 36 to the header 31 to cooperate with the front wall I4 in defining a passage 43 which leads upwardly from the front portion of the combustion chamber and between the front portions of the water tubes 34. A baille 44 extends upwardly and rearwardly from the headers 31 along the water tubes 4D and the lower row of water tubes 34 to cooperate with the roof I6 in defining a rearwardly tapering passage 45. The water tubes 4I support an upright baille 41 having a forward extension 48 at its lower end which cooperates with the baille 44 in defining a forwardly tapering passage 49 located beneath the passage 45. These passages 45 and 49 communicate between the baille 41 and the rear edge of the baille 44. Beneath the baille 48 there is provided a rearwardly extending passage I which leads to the lower portion of the tube bank I2. The passages 49 and 5I communicate between the roof 38 and the front edge of the baille 48. The baille 41 is spaced forwardly from the tube bank I2 to form a passage 52 which leads downwardly from the rear end of the upper passage to the lower passage 5I, this passage 52 having a damper 53 therein. A baille 55 extends downwardly adjacent the front portion of the tube bank I2 from the upper drum I9 and terminates somewhat above the lower drum I I to allow the gases to flow into the tube bank and then upwardly to an outlet duct 56 behind the upper drum. The upwardly flowing gases are deected intoa tortuous course by means of a series of staggered transverse bailles 51.

Before the gaseous products of combustion reach the tube bank I2 they are utilized to superheat the steam. For thispurpose a high temperature superheater 59 is mounted in the gas passage 45, and a low temperature superheater 6D is located in the passage `49. Each of these superheaters comprises a series of laterally spaced tubes each formed with a considerable number of upright loops providing a sinuous construction. The front end of the low temperature superheater 6D is connected to the steamspace of the drum I9 by means of a row of tubes BI which extend downwardly in front of the baille 41. The rear ends of the two superheaters are joined by a row of upright tubes 63, and the front end of the high temperature superheater 59 is connecteddirectly to a transverse outlet header 64 located above the roof I5. It will be apparent that the general direction of travel of the steam will be rearwardly through the low temperature superheater 69 and then forwardly through the high temperature superheater 59,.in counterflow heat transfer relation to the gases flowing through the passages 45 and 49.

In order to support the high temperature superheater 59 and the portion of the roof I5 adjacent thereto I provide several transverse lbars 66 each shaped as an inverted T in cross-section, the ends of the bars being suitably connected to the supporting framework of the boiler. The flanges of the bars 66 support the ends of beams 61 in the formof upright plates with their lower edges welded to the superheater tubes 59, as bestshown in Fig. 3. Certain loops 69 of the tubes 59 are extended upwardly and pass over the bars 66, these loops being slightly offset laterally from the beams 61, as shown in Fig. 4, to avoid interference. The low temperature superheater 60 may be suspended in any suitable manner from the water tubes 34 and 40.

The operation4 of the invention will now be apparent from the above disclosure. A suitable fuel, such as gas or oil, is introduced through the opening 2| and burned in suspension in the combustion chamber I9. Heat from the burning fuel is radiated to the surrounding water wall tubes, thus generating steam which is delivered to the drum I0, where the Water is separated from the steam. The steam flows from the drum I0 through the tubes 6I to the front end of the superheater 69, rearwardly through this superheater, upwardly through the tubes 63 to the rear'end of the superheater 59, and then forwardly through this superheater 59 to the outlet header 64. The gaseous products of combustion flow upwardly from the combustion chamber through the passage 43 and then rearwardly through the passages 59. The gases then divide, a portion flowing rearwardly over the top of the baille 41 and downwardly throughthe passage 52, and the remainder flowing downwardly in front of the baille 41, forwardly through the passage 49, and then downwardly and rearwardly through the passage 5I to rejoin the gases from the passage 52. The combined gases then enter the water tube bank I2 and flow upwardly in contact therewith until they finally escape through the outlet duct 55. The flow of the hot ygases past the two superheaters is opposite to the general direction of the steam flow through the superheaters resulting in eilcient transferof heat to the steam. By adjusting the damper` 53 the operator can control the flow of the gases in the passage 52, and thus direct a greater orless proportion of the gases into contact with the low temperature superheater 69. In this manner it is possible to regulate the final temperature of the steam delivered to the outlet header 64 The various bailies are all supported and cooled by water tubes through which a rapid natural `circulation is maintained. Such a baille construction is highly eifective and it will havea long life of useful service. The arrangement of the two superheaters is particularly compact,.it provides a large superheater surface, and it permits a gradually decreasing cross-sectional area for the gas passages to ensure maintenanceof adequate gas velocities despite reduction intemperature and volume. Because of the lack of appreciable convection heating surface ahead of the superheaters, the gases will reach the superheater 59 at a high temperature, and it is feasible to superheat the vsteam to a high temperature. The high temperature superheater 59, and particularly the front portion thereof, should be made of a high quality heat resisting metal or alloy. If after long service a portion of this up'- per superheater should require replacement, it is a simple matter to cut the adjacent loops 69 and remove the desired sections upwardly, whereupon a new section can be lowered into position and the ends thereof welded to the severed ends. of the loops.

Having thus described my invention, what .I claim as new and desire to secure by Letters Patent is: .y

1. A steam generator comprising a setting, a

transverse steam-andewater drum in the rear.f

direction therethrough andthence ltothe rearv portionof the setting, a transverse water drum beneath the steam-and-water drum, a considerable number of 'transverse rowsv of upright water tubes connecting the drums to provide a tube bank, a combustion chamber in the lower portion of the setting, a high-temperature superheater in the upper portion of the setting in front of the tube bank, a low-temperature superheater beneath the high-temperature superheater, means to deliver steam from the steam-and-water drum to the low-temperature superheater and thence to the high-temperature superheater, and ymeans to direct hot gases from the combustion chamber into contact successively with the high-temperature superheater,the low-temperature superheater, and the tube bank. f

2. A steam generator comprising a, setting, a transverse.steam-and-water drum in the lrear portion of the setting, a transverse water drum beneath the steam-and-water drum, a considerable number of transverse rows of upright water tubes connecting the drums to provide a tube bank, a combustion chamber in the lower portion of the setting, a high-temperature superheaterjn the upper portion of the setting in front of the tube bank, a low-temperature superheater beneath the high-temperature superheater, means to deliver steam from the steam-and-water drum to the low-temperature superheater and thence to the high-temperature superheater, a passage to conduct hot gases upwardly from the combustion chamber and in front of the low-temperature superheater to the high-temperature superheater, and means to direct the gases downwardly from the high-temperature superheater to the low temperature superheater and thence rearwardly to the said tube bank.

-3. A steam generator comprising a setting, a transverse steam-and-water drum in the rear portion of the setting, a transverse water drum beneath the steam-and-water drum, a bank of upright water tubes connecting the drums, a combustion chamber in the lower portion of the setting, a high-temperature superheater in the upper portion of the setting in f ront of the tube bank, a low-temperature superheater beneath the high-temperature superheater, means to deliver steam from the steam-and-water. drum to the front portion of the low-temperature superheater for flow in a generally rearward direction therethrough and thence to the rear portion o f the high-temperature superheater for flow in a generally forward direction therethrough, and means to direct hot gases from the combustion chamber upwardly and then rearwardly in contact with the i high-temperature superheater, downwardly and then forwardly in contact with the low-temperature superheater, and downwardly and rearwardly for eventual flow in contact with the tube bank 4. A steam generator comprising a setting, a transverse steam-and-water drum in the rear portion of the setting, a transverse water drum beneath the steam-and-water drum, a bank of upright water tubes connecting the drums, a combustion chamber in the lower portion of the setting, a high-temperature superheater in the upper portion of the setting in front of the tube bank, a low-temperature superheater beneath the high-temperature superheater, each of said superheaters including a series of laterally spaced tubes each formed with a considerable number of upright loops providing a' sinuous construction, means to deliver steam from the Steam-and-water drum to the front portion of the low-temperature superheater for flow in a generally rearward portion-of the high-temperature superheater for flow vin a generally forward Y"c'lirection y"therethrough, andmeans to direct'ho't gases fromjthe combustion chamber upwardly and then rearwardly in contact with the' high-temperature' superheater, `downwardly and then forwardly in contact with the low-temperature superheater, and ldownwardly "and rearwardly for eventual flow in contact with the tube bank.

5. A steam generator comprising a setting, a transverse steam-and-water drum in the rear portion of the setting, a transverse water drum tube bank, a forwardly tapering lower passage' beneath the upper (passage, the rear endsof the two passages being connected, a passage connecting the combustion chamber with the front end ofl the upper passage, a passage connecting the front end of the lower passagewith the-tube bank, a high-temperature superheater inthe upper passage, a rlow-temperature superheater in the lower passage, and means to deliver steam from the steam-and-water drum to the front portion of the low-temperature superheater for flow in a generally rearward direction therethrough and thence to the rear portion of the high-temperature superheater for flow in a generally forward direction therethrough.

6. A steam generator comprising a setting, a transverse steam-and-water drum in the rear portion of the setting, a transverse water drum beneath the steam-and-water drum, a bank of upright water tubes connecting the drums, a combustion chamber in the lower portion of the setting, a rearwardly directed upper passage in the upper portion of the setting in front of the tube bank, a forwardly directed lower passage beneath the upper passage, the rear ends of the two passages being connected, a passage extendl direction therethrough and thence to the rear portion of the high-temperature superheater for flow in a generally forward direction therethrough.

7. A steam generator comprising a setting, a transverse steam-and-water drum in the rear portion of the setting, a transverse water drum beneath the steam-and-water drum, a bank of upright water tubes connecting the' drums, a combustion chamber in the lower portion of the setting, a rearwardly directed upper passage in the upper portion of the setting in front of the tube bank, a forwardly directed lower passage beneath the upper passage, the rear ends of the two passages being connected, a passage extending upwardly from the combustion chamber to the front end of the upper passage, a passage extending from the front end of the lower passage downwardly and rearwardly to the lower portion of the tube bank, a by-pass extending from the rear end of the upper passage downwardly in front of the tube bank to the lower portion thereof, a; damper in the by-pass, ahigh temperature superheater in the upper passage, a low-temperature superheater in the lower passage, and

wall, a transverse header above the combustion chamber and spaced from the front wall of the setting, a row of water tubes extending forwardly from thev upper portion of the said rear Wall to the header, refractory material supported by the said row of tubes providing a roof for the combustion chamber, a row of water tubes extending upwardly and rearwardly from the header to the steam-and-Water drum, a baffle extending upwardly and rearwardly from the header adjacent the last-mentioned water tubes to cooperate with the roof of the setting in defining an upper passage having its front end connected directly with the `combustion chamber therebeneath to receive hot gases rising therefrom, anruprght baie behindY the first-mentioned baiiie` and having a forward extension at its lowerend beneath the first-mentioned baffle to cooperate therewith in defining Aa lower passage having its front end connected directly with the bank of water tubes, a row lof water tubes arranged in supporting `relation to the last-mentioned baffle, the rear ends ofthe two passages communicating in front of Vthe upright baiile, a high-temperature superheater in the upper passage, a 10W-temperature superheater in the lower passage, vand means to deliver steam from the steam-and-water drum to the front portion of the low-temperature superheater for flow in a generally rearward direction therethrough and thence to the rear portion of the high-temperature superheater for iiow in a generally forward direction therethrough.

MAX H. KUHNER. 

